This present preferred embodiment concerns a method and a device for engraving printing cylinders for packaging printing and similar printing applications in an electronic engraving machine in which an engraving member engraves elements to be printed (in particular made up of cups) into the printing cylinders, and the engraving member for areal engraving executes a feed movement parallel to the longitudinal axis of a printing cylinder. To shorten the engraving time, an engraving member can be associated with a respective circumferential engraving strip when a print image or layout for a respective printing cylinder is sub-divided into at least two of such circumferential engraving strips parallel to one another and next to each other in the axial direction.
An electronic engraving machine for engraving printing cylinders is known from DE-C-25 087 34. An engraving member with an engraving tool controlled by an engraving control signal as a cutting tool moves along a rotating printing cylinder in the axial direction. The engraving element cuts cups into the generated surface of the printing cylinder, which cups are arranged in an engraving grid in the manner of engraving lines. The engraving control signal is obtained by superimposing a periodic raster signal with image signal values which represent the tone values to be engraved. While the raster signal produces an oscillating lifting motion of the engraving tool to engrave the cups arranged in the engraving grid, the image signal values determine the geometric dimensions of the cups corresponding to the tone values to be engraved. According to the preferred embodiment, laser engraving tools could also be considered as engraving members. Instead of rotogravure cylinders with cups, cylindrical flexoprinting forms could also be engraved according to the preferred embodiment.
For magazine printing, for the most part the various print sides of a print job are simultaneously engraved with a respective engraving member on a printing cylinder on axially parallel, band-shaped cylinder regions called engraving lines.
However, for packaging printing and for similar printing applications (for example pattern or wallpaper printing) it is common practice (as is known from DE 199 47 397 A1) to engrave a printing cylinder in an engraving strip with only one engraving member. However, this procedure has the disadvantage that, in the engraving of large (in particular long) printing cylinders, long engraving times result that can amount to multiple hours. In contrast to this, the advantage is that no visible junctions (to which the human eye is very sensitive) arise in the engraved image.